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Anonymous Poster
rodmartin380@aol.com
Aug 28, 2009, 5:06 AM
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Jeep Grand Cherokee
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Hello, I'm Having problems with a 1997 Geep Grand Cherokee 4/4. It shut off sometimes while driving or sitting idleing just like someone turn the key. It starts back with no problem. I clean the fuel tank, replace the fuel pump, clean the injectors replaceed the relays and the computer nothing works and there is no check engine light. dont no what else to do but lite a match HELP.
Rod
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Hammer Time
Ultimate Carjunky
/ Moderator
Aug 28, 2009, 5:15 AM
Post #2 of 10
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Re: Jeep Grand Cherokee
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There is no way to know for sure what is wrong unless you have the ability to run a bunch of tests during the failure. Anything else is just guessing and we usually don't work that way. That being said, the crank sensor is a common failure that acts just like that.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Aug 31, 2009, 10:03 AM)
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Anonymous Poster
Aug 28, 2009, 7:15 AM
Post #3 of 10
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Re: Jeep Grand Cherokee
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how do i run test, it starts back like there is nothing wrong
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Hammer Time
Ultimate Carjunky
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Aug 28, 2009, 7:36 AM
Post #4 of 10
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Re: Jeep Grand Cherokee
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Then you can't test anything if it starts right back up. Your pretty much caught between a rock and a hard place when it comes to confirming anything.
Here is the procedure if it stays dead.
All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.
Every engine requires spark, fuel and compression to run. That's what we have to look for.
These are the basics that need to be tested and will give us the info required to isolate a cause.
1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.
2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.
3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.
Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Anonymous Poster
Aug 29, 2009, 2:55 AM
Post #5 of 10
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Re: Jeep Grand Cherokee
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what is the correct fuel pressure at idle speed
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Hammer Time
Ultimate Carjunky
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Aug 29, 2009, 3:39 AM
Post #6 of 10
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Re: Jeep Grand Cherokee
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What engine do you have?
Remember, checking the fuel pressure while the engine is running normally isn't going to tell you anything.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Aug 31, 2009, 10:03 AM)
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Anonymous Poster
Aug 31, 2009, 10:00 AM
Post #7 of 10
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Re: Jeep Grand Cherokee
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its a 4.0L V6.
I no i wont to see if the pressure drops when it cut off while idleing.
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Hammer Time
Ultimate Carjunky
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Aug 31, 2009, 10:05 AM
Post #8 of 10
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Re: Jeep Grand Cherokee
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The 4.0 is not a V6, it's an inline
Fuel Pressure
Engine at curb idle 338 ±14 kPa (49.2 ±5 psi)
Fuel Pressure Drop (pump not engaged) Not fall below 30 psi for 5 minutes
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Anonymous Poster
Aug 31, 2009, 10:13 AM
Post #9 of 10
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Re: Jeep Grand Cherokee
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ok, thanks let you no how it goes
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Anonymous Poster
Sep 1, 2009, 9:47 AM
Post #10 of 10
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Re: Jeep Grand Cherokee
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I check the fuel pressure with a gauge and it holds at 50 psi while the engine is running and it holds that psi when the engine cuts out. I have checked each injector and they all work, so i don't think thats it a fuel problem. what should i do now.
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